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Register a new userRecent atmospheric neutrino results from Soudan 2
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T. Kafka
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An updated measurement of the atmospheric nu_mu/nu_e ratio-of-ratios, 0.68+-0.11+-0.06, has been obtained using a 4.6-kty exposure of the Soudan-2 iron tracking calorimeter. The L/E distributions have been analyzed for effects of nu_mu -> nu_x oscillations, and an allowed region in the Delta m^2 vs. sin^2 2 theta plane has been determined.
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Neutrino interactions recorded in a 5.1 fiducial kiloton-year exposure of the Soudan-2 iron tracking calorimeter are analyzed for effects of neutrino oscillations. Using contained single track and single shower events, we update our measurement of the atmospheric nu_mu/nu_e ratio-of-ratios and find R = 0.68 pm 0.11 pm 0.06. Assuming this anomalously low R-value is the result of nu_mu flavor disappearance via nu_mu to nu_tau oscillation, we select samples of charged current events which offer good resolution, event-by-event, for L/Enu reconstruction. Oscillation-weighted Monte Carlo events are fitted to these data events using a chisq function summed over bins of log(L/E_nu). The region allowed in the (sin^2 2theta, Delta m^2) plane at 90% CL is obtained using the Feldman-Cousins procedure: 0.46 < sin^2 2theta < 1.0 and 2.2x10^-4 < Delta m^2 < 2.2x10^-2 ev^2. A small but relatively energetic sample of partially contained nu_mu events has also been isolated. Their distribution in log(L/E_vis) relative to null oscillation Monte Carlo is compatible with nu_mu to nu_tau oscillation scenarios within the parameter region allowed by our contained events.
A new measurement of the atmospheric numu/nue ratio-of-ratios, 0.61 +- 0.15 +- 0.05, has been obtained using a 3.2-kty exposure of the Soudan-2 underground detector. This measurement, based upon neutrino reactions in an iron tracking calorimeter of honeycomb-lattice geometry, is in agreement with the anomalously low value reported by the underground water detectors.
The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 +- 0.19 +0.05 -0.07 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown not to produce low values of the ratio.
The most recent results from the KLOE experiment are presented, covering: the measurement of the running fine-structure constant alpha_em,the Dalitz plot measurement of eta to pi+pi-pi0, the search of a U boson, tests of discrete symmetries and quantum coherence. The KLOE-2 Collaboration will take data until mid 2018 aiming to collect 5 inversed fb increasing the data set, in order to produce new precision measurements and continue studies of fundamental symmetries and New Physics.
While neutrino physics enters precision era, several important unknowns remain. Atmospheric neutrinos allow to simultaneously test key oscillation parameters, with Super-Kamiokande experiment playing a central role. We discuss results from atmospheric neutrino oscillation analysis of the full dataset from Super-Kamiokande I-IV phases. Further, we discuss tests of non-standard neutrino interactions with atmospheric neutrinos in Super-Kamiokande.
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